OPIS'

closest English equivalent "series" or "subgroup"

often arranged by date or subinstitution

e.g. GARF f.1235, op.1, II sozyv--October 1917 op.2, 3rd Congress of Soviets op. 140 (former f.1235 s.ch [sekretnaia chast'] - a collection declassified after 1991 By the way, the term opisi is also used to describe the "inventories" or "registers" that list and often describe the files in a fond -- enormously valuable (once "for service use only" - and still restricted in some archives). This will be described more fully below.

DELO

(or file designation- especially edinitsy khraneniia or ed. khr.) These are the actual files (folders or boxes) that contain the LISTY (often filed this way at origin -- by dates or themes). e.g. several dela in op.140 were designated "anti-Soviet letters from the population"

A full citation would be, for instance:

GARF, f. 1235, op.1, d. [or ed. khr.] 16, ll. 5-7ob. (if not obvious from the text, include descriptive details or the title of the document)

NOTE: Some archives use other citation systems - e.g. a typical cite from the Gorky archive would be:

"Arkhiv A. M. Gorkogo, KG-NP/A, 22-4:1-2"

Be sure to ask about citation systems!

Two general comments on citing in your work:

determine the standard in the field.

include substantive information (not just numbers, since these change).